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b=ImpItil6G3hWJVCbd3i8tE1QJSz9GrF9Y0HICLelQ0bavFlm3EZl/LdcX3TUkENnWNoVEGT2FRXTM++6h8EmgguY4ZkO2psOTzRrB05JsoAqtLPeIjZZ30gno6h4oi/lwj9zoLHWXcALcXFELBz/lwxcRLoBXQ8ChcxBZfDrsos= Received: from 30.74.144.118(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wv1ZCXw_1765941096 cluster:ay36) by smtp.aliyun-inc.com; Wed, 17 Dec 2025 11:11:37 +0800 Message-ID: <8bfcae1c-74a0-43e8-807b-fff22a770241@linux.alibaba.com> Date: Wed, 17 Dec 2025 11:11:35 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] mm: rmap: support batched unmapping for file large folios To: Lorenzo Stoakes Cc: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, david@kernel.org, catalin.marinas@arm.com, will@kernel.org, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <70d1dedc-b4fc-4eb6-baf6-9e54b6a62249@lucifer.local> <9e038290-70ff-458d-b46d-bc512c3442be@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: BC205C0008 X-Rspamd-Server: rspam03 X-Stat-Signature: 7hnrec3uqixs7hyxrhz47mbxff7bkzwb X-Rspam-User: X-HE-Tag: 1765941100-705793 X-HE-Meta: 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 nSIlInih QJGBmuizOlyUQzMCzyY2Yqw+W4b5imc3qBroJqM4YrBWXP3+iK+JOKyHACMGq0kkcXBCgtG4zfBOgwcfVHD9gL3jWKJ4uWm3l1mQHuykmtfIR96gpkC8jDJvMuwJ03d/chSln7d7ed5/7BS5T1ddXulzrSkT8sreLpCfl3bsczGx5N12AypQ6/iCbPBtGN2rH6VdxOBBDq9o5+fiQk0waMHHqxvS+QFaLZqPEgKasGk8Wbck2fgnEJP+kg022Vz7K+F2V+bb73P5xWhaLbWjDzKGZ/WXpWARD1AcrN/pSskO6yI8gzFgaR6f8FW95ovzRopSeHDGqXtndouJirsUmRPH+hg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/12/16 18:54, Lorenzo Stoakes wrote: > On Tue, Dec 16, 2025 at 02:22:11PM +0800, Baolin Wang wrote: >> >> >> On 2025/12/16 14:13, Barry Song wrote: >>>>>> >>>>>> diff --git a/mm/rmap.c b/mm/rmap.c >>>>>> index ec232165c47d..4c9d5777c8da 100644 >>>>>> --- a/mm/rmap.c >>>>>> +++ b/mm/rmap.c >>>>>> @@ -1855,9 +1855,10 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, >>>>>> end_addr = pmd_addr_end(addr, vma->vm_end); >>>>>> max_nr = (end_addr - addr) >> PAGE_SHIFT; >>>>>> >>>>>> - /* We only support lazyfree batching for now ... */ >>>>>> - if (!folio_test_anon(folio) || folio_test_swapbacked(folio)) >>>>>> + /* We only support lazyfree or file folios batching for now ... */ >>>>>> + if (folio_test_anon(folio) && folio_test_swapbacked(folio)) >>>>> >>>>> Why is it now ok to support file-backed batched unmapping when it wasn't in >>>>> Barry's series (see [0])? You don't seem to be justifying this? >>>> >>>> Barry's series[0] is merely aimed at optimizing lazyfree anonymous large >>>> folios and does not continue to optimize anonymous large folios or >>>> file-backed large folios at that point. >>> >>> Yep. At that time, I didn’t have an Android machine with a filesystem >>> that supported large folios, so I focused on lazyfree. But I >>> agree that lazyfree anon folios and file folios are quite >>> similar. >>> >>>> >>>> Subsequently, Barry sent out a new patch (see [1]) to optimize anonymous >>>> large folios. As for file-backed large folios, the batched unmapping >>>> support is relatively simple, since we only need to clear the PTE >>>> entries for file-backed large folios. >>> >>> Yep. It is actually quite straightforward to go from lazyfree >>> anon folios to file folios. Swap-backed anon folios are much >>> more tricky, though. >> >> Agree. Thanks Barry for reviewing and confirming. > > OK that makes me less concerned, but you do need to put some more justification > in the commit message. Sure. Will do.